unittest in Tryton: suite

Each module must define a suite method
under trytond.module.<name>.tests.suite()
which return a TestSuite

def suite():
    suite = trytond.tests.test_tryton.suite()
    suite.addTests(
            unittest.TestLoader().loadTestsFromTestCase(
            SaleTestCase))
    suite.addTests(doctest.DocFileSuite(
            'scenario_sale.rst',
            setUp=doctest_setup,
            tearDown=doctest_teardown,
            encoding='utf-8',
            optionflags=doctest.REPORT_ONLY_FIRST_FAILURE
            ))
    return suite